Swing/WatermarkInTextField のバックアップ(No.8)

class WatermarkTextField extends JTextField implements FocusListener {
  private final ImageIcon image;
  private boolean showWatermark = true;
  public WatermarkTextField() {
    super();
    image = new ImageIcon(getClass().getResource("watermark.png"));
    addFocusListener(this);
  }
  @Override public void paintComponent(Graphics g) {
    super.paintComponent(g);
    if(showWatermark) {
      Graphics2D g2d = (Graphics2D) g;
      //Insets i = getMargin();
      Insets i = getInsets();
      int yy = (getHeight()-image.getIconHeight())/2;
      g2d.drawImage(image.getImage(), i.left, yy, this);
    }
  }
  @Override public void focusGained(FocusEvent e) {
    showWatermark = false;
    repaint();
  }
  @Override public void focusLost(FocusEvent e) {
    showWatermark = "".equals(getText().trim());
    repaint();
  }
}